Numerous monoclonal antibodies have been developed which have binding specificity for a variety of human carcinomas (see Schlom, J. et al, Important Advances in Oncology, Philadelphia, Pa., J.B. Lippincott Co., Vol. 1, pp. 170-192 (1984) and Schlom, J., Cancer Res., 46: 3225-3238 (1986). One of these monoclonal antibodies designated B72.3 (see Colcher, D. et al, Proc. Natl. Acad. Sci. USA. 78: 3199-3203 (1981) and U.S. Pat. Nos. 4,522,918 and 4,612,282), is a murine IgG.sub.1, and was developed using a human breast carcinoma extract as the immunogen. Monoclonal antibody B72.3 is produced by hybridoma B72.3 (ATCC No. HB-8108) and has been extensively studied. Monoclonal antibody B72.3 has been shown to be distinct from other known monoclonal antibodies on the basis of: (1) its binding specificity to TAG-72 (see Johnson, V. G. et al, Cancer Res., 46: 859-857 (1986)); (2) its binding specificity to various types of human carcinoma tissues, including breast, ovarian, lung, colorectal, endometrial and pancreatic carcinoma tissues (see Nuti, M. et al, Intl. J. Cancer, 29: 539-545 (1982); Stramignoni, D. et al, Intl. J. Cancer, 31: 543-552 (1983), Thor, A. et al, J. Natl. Cancer Inst. 76: 995-1006 (1986); and Thor, A. et al, Cancer Res., 46: 3118-3124 (1986)); (3) its lack of binding specificity to normal adult human tissues (see Nuti, M. et al, Intl. J. Cancer, 29: 539-545 (1982); Stramignoni, D. et al, Intl. J. Cancer, 31: 543-552 (1983); Thor, A. et al, J. Natl. Cancer Inst., 76: 995-1006 (1986); and Thor, A. et al, Cancer Res., 46: 3118-3124 (1986)); (4) its ability to detect TAG-72 in serum (see Paterson, A. J. et al, Int. J. Cancer, 37: 659-666 (1986) and Klug, T. L. et al, Int. J. Cancer, 38: 661-669 (1986)); (5) its ability to detect carcinoma cells in human effusions and fine needle aspiration biopsies (see Szpak, C. A. et al, Acta Cytologica, 28: 356-367 (1984); Johnston, W. W. et al, Cancer Res., 45: 1894-1900 (1986); Szpak, C. A. et al, Am. J. Path., 122: 252-260 (1986); Johnston, W. W. et al, Human Path., 17: 501-513 (1986); Martin, S. E. et al, Am. J. Clin. Path, 86: 10-18 (1986); Nuti, M. et al, Int. J. Cancer, 37: 493-498 (1986) and Johnston, W. W. et al, Cancer Res., 46: 6462-6470 (1986)); and (6) its binding specificity and prolonged binding to human carcinomas both in experimental animal systems (see Keenan, A. M. et al, J. Nucl. Med., 25: 1197-1203 (1984) and Colcher, D. et al, Cancer Res., 44: 5744-5751 (1984)) and in clinical trials (see Colcher, D. et al, Cancer Res., 47: 1185-1189 (1987) and Esteban, J. M. et al, Int. J. Cancer, 39: 50-58 1987)).
However, monoclonal antibody B72.3 is disadvantageous in that (1) B72.3 does not have binding specificity to every human carcinoma tissue of a particular type, e.g., to every ovarian, colon carcinoma tissue, etc. (see Nuti, M. et al, Intl. J. Cancer, 29: 539-545 (1982); Stramignoni, D. et al, Intl. J. Cancer, 31: 543-552 (1983); Thor, A. et al, J. Natl. Cancer Inst., 76: 995-1006 (1986); Thor, A. et al, Cancer Res., 46: 3118-3124 (1986) and Horan Hand, P. et al, Cancer Res., 42: 728-735 (1983)); (2) B72.3 does not have binding specificity to all carcinoma cells within a given human carcinoma mass (see Nuti, M. et al, Intl. J. Cancer, 29: 539-545 (1982); Stramignoni, D. et al, Intl. J. Cancer, 31: 543-552 (1983); Thor, A. et al, J. Natl. Cancer Inst., 76: 995-1006 (1986); Thor, A. et al, Cancer Res., 46: 3118-3124 (1986) and Horan Hand, P. et al, Cancer Res., 43: 728-735 (1983)); (3) B72.3 does not have binding specificity to most human carcinoma cell lines in culture (see Horan Hand, P. et al, Cancer Res., 43: 728-735 (1983); Horan Hand, P. et al, Cancer Res., 45: 833-840 (1985) and Friedman, E. et al, Cancer Res., 45: 5648-5655 (1985)); (4) it is difficult to obtain highly immunoreactive F(ab').sub.2, F(ab') and Fab fragments from B72.3, such fragments being necessary for efficient in vivo immunodiagnostic and therapeutic applications; and (5) since B72.3 is of the IgG.sub.1 isotype, it is difficult to conduct monoclonal antibody effector cell mediated cytotoxicity or complement mediated cytotoxicity studies using B72.3 (IgG.sub.2a, IgG.sub.2b or IgM isotypes being more efficient for these applications).